The latest Guy Ritchie flick "The Ministry of Ungentlemanly Warfare" has a spine of true story to it, even if it does all it can to amplify a long-declassified World War II tale with enough dead Nazis to make "Inglourious Basterds" blush.

The result is a jauntily entertaining film but also an awkward fusion. Ritchie's film, open in theaters now, takes the increasingly prolific director's fondness for swaggering, exploitation-style ultraviolence and applies it to a real-life stealth mission that would have been thrilling enough if it had been told with a little historical accuracy.

In 2016, documents were declassified that detailed Operation Postmaster, during which a small group of British special operatives sailed to the West African island of Fernando Po, then a Spanish colony, in the Gulf of Guinea. Spain was then neutral in the war, which made the Churchill-approved gambit audacious. In January 1942, they snuck into the port and sailed off with several ships — including the Italian merchant vessel Duchessa d'Aosta — that were potentially being used in Atlantic warfare.

Sounds like a pretty good movie, right? The story even features James Bond author Ian Fleming, giving it more than enough grist for a WWII whopper. "Operation Postmaster" makes for a better title, too, than the ungainly "The Ministry of Ungentlemanly Warfare." Ritchie, however, already has an operation — last year's "Operation Fortune: Ruse de Guerre" — in his filmography.

Ritchie, who turned Sherlock Holmes into a bulked-up action star, has always preferred to beef up his movies. It's a less-noted side effect of the superhero era that regular ol' heroes have been supersized, too, as if human-sized endeavors aren't quite enough anymore. And "The Ministry of Ungentlemanly Warfare," in which a handful of operatives kill approximately a thousand Nazis, has a fine, brawny duo in Henry Cavill and Alan Ritchson.

In the movie's opening scene, they're relaxing on a small ship in the Atlantic when Germans rush aboard. After a few laughs and a Nazi monologue that plays like a poor man's version of Christoph Waltz's masterful oration in "Inglourious Basterds," the duo makes quick mincemeat of them, leaving blood splattered across the henley shirt of Anders Lassen (Ritchson, a charming standout).

Not much has changed in Ritchie-land, though he's swapped tweed for skintight tees and cable-knit sweaters in a rollicking high-seas adventure. As in the director's previous movies, everyone — and, as before, nearly all male — seems to be having a good time. Likewise, Ritchie revels in his characters' debonair nonchalance while meting out all manner of savagery.

The assembled group of operatives are said to be delinquents and misfits, though they steadfastly adhere to the polite manners of past Ritchie protagonists. They may kill with bloodthirsty impunity but what really matters is upholding an old-school sense of style. When the undercover agents Marjorie Stewart (Eiza González, who silkily cuts like a knife through the film) and Mr. Heron (Babs Olusanmokun, excellent) ride a Nazi-controlled train on their way to Fernando Po, they look in disgust at the German sausages they're served. Later, someone will say, "I hate Nazis not because they're Nazis but because they're so gauche."

And in proficiently staged set pieces, Ritchie makes his own case for a bit of class. As a journeyman filmmaker now pumping out a movie a year, he's in many ways grown to be a more complete director. He's adept at giving the many members of his large ensemble moments to shine — including Henry Golding, Alex Pettyfer, Cary Elwes, Freddie Fox as Fleming, Til Schweiger as a barbaric Nazi and Rory Kinnear as Churchill.

And once the film — based on the nonfiction book by Damien Lewis — settles into a seedy, sunny West African setting and the nighttime heist finale, "The Ministry of Ungentlemanly Warfare" proves a spirited, if grossly exaggerated diversion.

"The Ministry of Ungentlemanly Warfare," a Lionsgate release, is rated R by the Motion Picture Association for strong violence throughout and some language. Running time: 92 minutes. Two and a half stars out of four.